Nuclear expression of p63, involucrin and 34betaE12 were detected indicating squamous differentiation. Cytoplasmic p63 expression was also identified. The fact that the Ki-67 labeling index was significantly higher in such cases may have been associated with the aggressive behavior of these tumors. Our findings suggest that the characteristic morphology of invasive micropapillary carcinomas may be due to immunophenotypical and oncogenic changes.

Metaplastic breast cancers (MBCs) [spindle cell carcinoma (SpCC), squamous cell carcinoma (SCC), and matrix-producing carcinoma (MPC)] and invasive carcinomas with central acellular zones (CACs) were analyzed with respect to biological potential by immunohistochemical analyses. Specimens from 40 patients [20 with MBCs (7 with SCC, 6 with SpCC, 5 with MPC, and 2 with mixed type)] and 20 with CACs were analyzed using antibodies to cytokeratin (CK) 8, 5/6, 14, AE1/AE3, 34αE12, involucrin, c-kit, vimentin (VIM), alpha-smooth muscle actin, p63, epidermal growth factor receptor, epithelial cell adhesion molecule, and estrogen receptor (ER)/progesterone receptor (PR)/HER2. Expression of CK5/6, 34βE12, VIM, nuclear p63, and cytoplasmic p63 was significantly higher with MBCs than CACs (38%/13%, 70%/43%, 85%/33%, 68%/40%, and 48%/18%, respectively). Other markers were expressed at various levels in these tumors, but the difference between them was not significant. Eighteen MBC and 8 CAC cases were triple (ER/PR/HER2) negative; 17 MBCs and 7 CACs were basal-like tumors. Several differences were seen in MBCs and CACs, but they were heterogeneous, differentiating multipotentially into mesenchymal, myoepithelial, basal-like phenotypes with "stem cell-like" features. Thus, CACs are related to MBCs by immunohistochemical analyses as well as according to morphological findings.

No abstract

Nuclear findings, including size, shape, chromatin, or nucleoli, affect the cytological diagnosis and were found to have prognostic significance in several studies based on morphometric analysis. In this study, we investigated whether the nucleus area relates to the appearance of p63-positive myoepithelial cells. The nucleus area was analyzed in 101 breast cancers and 14 benign breast lesions using morphometric analysis and immunohistochemistry for p63. Breast cancer patients were classified into two groups; small nucleus group (n = 19) and large nucleus group (n = 82) based on the average nucleus area of ductal cells. The nucleus area was significantly negative correlating with p63-positive myoepithelial cells (P = 0.031), and there was a significant positive correlation with small cells with hyperchromatic nuclei (P = 0.002). Although small cells with hyperchromatic nuclei were similar to myoepithelial cells, there was no significant correlation with the appearance of small cells with hyperchromatic nuclei and p63-positive myoepithelial cells in breast cancer patients (P = 0.189). Although the identification of normal myoepithelial cells is mainly performed by immunostaining for p63, morphometric analysis of the nucleus area also suggests the existence of p63-positive myoepithelial cells.